In recent years, attention has been directed to an alkali metal nitride or an alkaline earth metal nitride as a material such as a raw material of aluminum nitride used for a semiconductor device, a metal sliding member, an electrode construction material and the like. A high-purity product is required for the metal nitride used for the applications.
Examples of a conventional method for producing an alkali metal nitride and an alkaline earth metal nitride include a method for heating alkaline earth metals such as calcium in a nitrogen gas stream (Non Patent Literatures 1 and 2).
However, this method nitrides only the surfaces of these metals, and has difficulty in nitriding the inside thereof. Therefore, the metal nitride obtained by the method cannot be used for the above-mentioned application requiring a high-purity product.
Another method is a method for heating calcium with ammonia, a problem of which method is production of calcium hydride as a by-product (Non Patent Literature 3). Furthermore, yet another method is a method for heating tricalcium tetranitride to 250° C., problems of which are explosiveness and toxicity (Non Patent Literature 4).
Furthermore, there is disclosed a method for reacting a molten zinc-calcium alloy with a heated and pressurized nitrogen jet to synthesize calcium nitride (Patent Literature 1). However, this method requires a special device, and thus it is difficult to say that the method is an industrially advantageous method.